<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>太极图</title>
	<style>
		body{
			background-color: skyblue;
		}
		.box{
			position: relative;
			width: 0;
			height: 400px;
			margin: 100px auto 0;
			border-left: 200px solid #fff;
			border-right: 200px solid #000;
			border-radius: 50%;
			animation: box 10s linear infinite;
		}
		.box:before{
			display: inline-block;
			position: absolute;
			content: "";
			background-color: #fff;
			left: -20px;
			top: 80px;
			width: 40px;
			height: 40px;
			border-radius: 50%;
			box-shadow: 0 0 0 80px #000;
		}
		.box:after{
			display: inline-block;
			position: absolute;
			content: "";
			background-color: #000;
			left: -20px;
			bottom: 80px;
			width: 40px;
			height: 40px;
			border-radius: 50%;
			box-shadow: 0 0 0 80px #fff;
		}
		.box:hover{
			animation-play-state: paused;	
		}
		@keyframes box{
			from{
				transform: rotate(0deg);
			}
			to{
				transform: rotate(360deg);
			}
		}
	</style>
</head>
<body>
	<div class="box"></div>
</body>
</html>